Purpose or Case Report: Thyroid hemiagenesis (TH) is a rare congenital abnormality associated with a higher incidence of thyroid disease. It is often asymptomatic and an incidental finding. However, TH may present as a palpable thyroid nodule, prompting sonography and thyroid function testing. Ultrasound (US) can differentiate between total absence of the thyroid lobe and severe hypoplasia. It is also useful for guiding fine needle aspiration when warranted. Scintigraphy is useful for determining the presence of ectopic thyroid tissue and to further characterize focal nodular thyroid lesions. Despite their respective roles, imaging findings on both US and scintigraphy can pose diagnostic challenges to the pediatric radiologist.

This educational poster will review the embryology of the thyroid gland, frequency of TH, clinical presentation and associations with additional thyroid anomalies such as malignancy, thyroiditis and abnormal gland function. Imaging features of TH will be reviewed with focus on (US) and scintigraphy.

The goals of this exhibit are:
1. Review the incidence and clinical presentation of pediatric patients with TH
2. Describe the imaging findings and role of ultrasound and scintigraphy in the diagnosis and follow-up of TH
3. Discuss prognosis and outcomes of TH in children
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